El Cinco (Spanish for The Five) is one of the 18 barrios of the municipality of San Juan, Puerto Rico and a former barrio of the dissolved municipality of Rio Piedras. As of the 2010 United States Census, it had a population of 6,198 and a land area of 1.34 square miles (3.5 km2) resulting in a population density of 4,625.4/sq mi (1,785.9/km2).